Predicting overall survival (OS) in patients (pts) with metastatic colorectal cancer (mCRC) treated with chemotherapy (CT): The British Columbia Cancer Agency (BCCA) mCRC score.

Abstract

3624 Background: The prognosis of individual pts with mCRC can be highly variable. Our objective was to develop a scoring system to improve the prognostication of mCRC pts at baseline assessment. We also further explored the impact of palliative resection (PR) of the primary tumor on OS. Methods: Pts diagnosed with mCRC from 2006 to 2008, referred to 1 of 5 regional cancer centers in British Columbia were retrospectively reviewed. Pts with prior early stage CRC who relapsed with mCRC were excluded. Multivariate stepwise selection was performed using significant variables from univariate analysis. Patients were assigned a composite risk score (range 0-15) based on their baseline variables, and then separated into quartiles for OS using cut-point analysis and Kaplan Meier methods. A secondary propensity score matched analysis was performed to obtain hazard ratios (HR) for death in order to control for baseline differences between pts who underwent PR and those who did not. Results: A total of 505 mCRC pts were included: median age 63 (range 22-86), 58% male, 75% ECOG 0-1, 58% colon primary, 34% >1 metastatic site, and 46% smokers. In this cohort, 81% of the population underwent PR. ECOG 2-3, no primary resection, colon primary, >1 metastatic site, CEA level >4 ng/ml, male gender, and smoker were significant in the multivariate model and subsequently assigned a score. Median OS varied significantly depending on the composite risk score (table). After ECOG PS, PR of the primary was the second strongest prognostic factor (HR 2.3, 95%CI 1.6-3.3). To further explore this, a propensity score matched analysis was performed adjusting for age, gender, ECOG and receipt of chemotherapy. Prognosis continued to be more favorable in the PR group with a median OS of 17 vs. 7.9 months (HR 0.66, 95% CI 0.50-0.86, p=0.0019). Conclusions: In this population based analysis, the BCCA mCRC score was a simple and effective method to improve prognostication for mCRC pts. PR of the primary was associated with significantly longer OS. [Table: see text]